In the prior art film less dental radiography, an X-ray beam is projected through the patient's tooth, but no photographic film is used. Instead, an electronic sensor is placed in the patient's mouth behind the tooth to be examined. The electronic sensor may include a charge-coupled device (CCD), an active pixel sensor (APS) array or any other film less radiation sensor. The X-rays pass through the tooth and impinge on the electronic sensor, which converts the X-rays into an electrical signal. The electrical signal is transmitted over a wire to a computer, either directly or through a module including intermediate processing circuitry. The computer then processes the signal to produce an image on an associated output device, such as a monitor or a printer.
However, in the prior art filmless dental radiography the noise level can be high enough and it is difficult to filter it out without extensive or expensive circuitry.